1. Field of the Invention
The present invention relates to an optical communications equipment used, for example, for high-density, optical frequency-multiplexed, optical networks.
2. Description of the Related Art
In recent years, Internet communications have become widespread at an amazing rate. With this trend, the communications transmission method is shifting to a method using optical fibers. Furthermore, in order to increase the transmission capacity further, WDM (Wavelength Division Multiplexing) utilizing optical multiplexing is being adopted. For this purpose, optical control communications modules for combining, splitting, switching, attenuating, and otherwise processing different wavelengths of optical signals are indispensable.
In some optical control communications modules, an optical control member such as a filter is made to move a very small distance, for controlling light. Other optical control communications modules make use of AWGs (arrayed-waveguide gratings) using optical waveguides.
A drive source is essential for the former type. Conventional optical communications modules have used electromagnetic motors or electromagnetic actuators such as stepping motors and servomotors.
Where a stepping motor is used as a drive source for an optical communications module, it is difficult to accurately place the optical control member in position and so limitations are placed on the resolution. Where a servomotor is used, it needs to be energized whenever the optical control member is placed in position. Hence, it is difficult to realize a latching structure.
Where an AWG (arrayed-waveguide grating) is employed, limitations are imposed on the amount of attenuation and on the resolution.
It is an object of the present invention to provide a highly reliable, optical communications equipment which controls light more accurately (i.e., less limitations are imposed on the amount of attenuation and on the resolution) and which has a latching function.
This object is achieved in accordance with the teachings of the present invention by an optical communications equipment comprising: a piezoelectric actuator using a deformation motion produced in a piezoelectric vibrating body as a power source; a moving body moved by the piezoelectric actuator as a drive source; an optical control unit for controlling light that is a signal medium as the moving body moves; and a drive control circuit for controlling the optical control unit via the piezoelectric actuator. If the moving body is not moved for a given time, the drive control circuit can send a function keeping signal to drive the piezoelectric actuator to such an extent that the moving body does not move or that transmission of the optical signal is not affected.